If you connect your system to a grounding rod I think it will increase the risk of electric shock
Yeah. Sometimes, but mainly not.
Today, in a lot of countries which have RCCDs mandatory on all circuits, as in my country, isolation transformers are more dangerous than non-isolated circuits.
You are not warned and put safe when you touch the first wire on an isolated circuit, you get the full shock with no protection directly when you touch the second.
On a 30mA RCCD, it never happens, there's nearly always a path to ground for 30mA, and you're protected, at least on 220V, less so on 110V
So I strongly recommend the TN-S earthing scheme if possibl, with a RCCD:
http://www.electrical-installation.org/enwiki/Definition_of_standardised_earthing_schemesBut beware!
The output of a non-isolated inverter is not a sinus with respect to battery- ( which is PE often)
The output of this inverter puts a half sine on one conductor, the other half sine on the other.
This is fine, but it adds a DC component to GND.
So if you use a RCCD downstream, please take one that also protects against DC faults.